What is the best course of action for a 16-year-old patient experiencing tachycardia, chest pain, and near syncope?

Immediate Hospitalization and Urgent Cardiac Evaluation Required

This 16-year-old patient with tachycardia, chest pain, and near syncope requires immediate hospitalization for evaluation, monitoring, and management, as this symptom triad in an adolescent represents a potentially life-threatening cardiac arrhythmia until proven otherwise. 1

Initial Emergency Assessment

Obtain a 12-lead ECG within 5 minutes of presentation to document the rhythm, heart rate, QRS duration, and identify any baseline abnormalities including pre-excitation (delta waves suggesting Wolff-Parkinson-White syndrome), prolonged QT interval, or Brugada pattern. 1, 2 This ECG is mandatory before any treatment that might terminate the rhythm, as capturing the arrhythmia on ECG is essential for definitive diagnosis. 2

Critical Immediate Actions:

• Assess hemodynamic stability first - check for acute altered mental status, hypotension, shock, or signs of acute heart failure, as this dictates whether immediate synchronized cardioversion is needed. 2
• Establish IV access and continuous cardiac monitoring. 2
• Obtain vital signs including orthostatic measurements if stable. 3
• Administer supplemental oxygen if needed. 2

Diagnostic Workup

Essential Testing:

• 12-lead ECG during tachycardia if the patient is still symptomatic - this is the single most important diagnostic tool. 1, 2
• Echocardiogram to exclude structural heart disease including hypertrophic cardiomyopathy (the most common cause of sudden cardiac death in adolescents), dilated cardiomyopathy, valvular abnormalities, and coronary artery anomalies. 1, 2
• Laboratory evaluation: complete blood count (anemia), thyroid function tests (hyperthyroidism), basic metabolic panel (electrolyte abnormalities), and toxicology screen. 3

Age-Specific Considerations:

For a 16-year-old, the upper limit of physiologic sinus tachycardia is approximately 204 bpm (220 minus age). 2, 3 However, the combination of tachycardia with chest pain AND near syncope elevates concern significantly beyond simple sinus tachycardia. 1

High-Risk Features Requiring Immediate Cardiology Consultation

Immediate cardiology referral is mandatory for: 2

• Pre-excitation (WPW syndrome) on ECG
• Syncope or near syncope during tachycardia or with exercise
• Wide complex tachycardia of unknown origin
• Documented sustained supraventricular tachycardia

This patient meets criteria for urgent cardiology consultation based on near syncope during tachycardia. 2

Differential Diagnosis Priority

Life-Threatening Conditions to Rule Out:

Ventricular arrhythmias: Despite the patient being young, 15% of patients with sustained ventricular tachycardia present with near syncope, and 27% experience chest pain. 4 Importantly, approximately 50% of patients with ventricular tachycardia have mild or no cerebral symptoms, leading to misdiagnosis as supraventricular tachycardia. 4 The differentiation must be based on ECG criteria, not symptom severity. 4

Supraventricular tachycardia (SVT): Tachycardia may cause syncope in ostensibly normal pediatric patients, with palpitations as the usual accompanying symptom, but other nonspecific symptoms such as chest pain, dyspnea, or near syncope may be present. 1 True syncope is infrequent with SVT but should be taken seriously in young patients. 3

Hypertrophic cardiomyopathy: Young age and syncope are risk factors for sudden cardiac death in these patients. 1 This is the most common cause of sudden cardiac death in adolescents. 1

Long QT syndrome or other channelopathies: These can present with syncope triggered by exercise or emotional stress. 1

Coronary artery anomalies: Present in approximately 1% of the population and can cause exercise-related symptoms. 1

Management Algorithm

If Hemodynamically Unstable:

• Proceed immediately to synchronized cardioversion starting at 50-100 J for SVT. 2
• Do not delay for IV access if patient is unstable. 2

If Hemodynamically Stable:

1. Obtain 12-lead ECG immediately to evaluate QRS duration and rhythm. 2

2. If narrow-complex regular tachycardia (QRS <120 ms):

   • Consider adenosine while preparing for cardioversion if SVT is suspected. 2
   • Evaluate RP interval: short RP (<90 ms) suggests AVNRT; longer RP suggests AVRT or atrial tachycardia. 1

3. If wide-complex tachycardia:

   • Assume ventricular tachycardia until proven otherwise. 2
   • Immediate cardiology consultation required. 2

4. If sinus tachycardia:

   • Identify and treat underlying cause (fever, dehydration, anemia, hyperthyroidism, anxiety). 2, 3
   • However, chest pain and near syncope with sinus tachycardia still warrant full cardiac evaluation to exclude structural disease. 1

Critical Pitfalls to Avoid

Do not assume benign etiology based on age alone. While neurocardiogenic syncope is common in healthy adolescents, the triad of tachycardia, chest pain, and near syncope requires exclusion of life-threatening cardiac conditions. 1

Do not use symptom severity to differentiate ventricular from supraventricular tachycardia. Ventricular tachycardia can present with mild symptoms, and this leads to misdiagnosis in approximately 50% of cases. 4

Recognize that persistent tachycardia can cause tachycardia-mediated cardiomyopathy, which is reversible but requires careful long-term follow-up. 2

In patients with poor cardiac function, cardiac output may be dependent on rapid heart rate - "normalizing" compensatory tachycardia can be detrimental. 2

Ambulatory Monitoring Indications

Class I indication for ambulatory ECG monitoring (Holter or event recorder): Syncope or near syncope associated with exertion when the cause is not established by other methods. 1 This patient meets this criterion.

Class IIa indication: Syncope, near syncope, or sustained palpitation in the absence of a reasonable explanation where there is no overt clinical evidence of heart disease. 1

Holter monitoring facilitates diagnostic and prognostic assessment in patients with syncope precipitated by chest pain, as it can document evolving ST changes or arrhythmias during symptomatic episodes. 5

Disposition

Admit to monitored bed (telemetry or intensive care unit depending on stability) for continuous cardiac monitoring, completion of diagnostic workup, and cardiology consultation. 1 Patients presenting with syncope for which ventricular arrhythmia is documented or thought to be a likely cause should be hospitalized for evaluation, monitoring, and management. 1

Do not discharge home without:

• Documented rhythm on 12-lead ECG
• Echocardiogram results
• Cardiology evaluation
• Exclusion of life-threatening structural or electrical cardiac disease

The combination of symptoms in this adolescent represents a Class I indication for urgent evaluation and cannot be managed in the outpatient setting. 1